This invention relates generally to animal litter containers of the type containing loose partiulate material therein, such as so-called "litter boxes", which are well suited for household use by domestic pets, such as cats, to deposit their excreta therein.
Such litter boxes are, of course, well known to the art. For example, U.S. Pat. No. 4,271,787 discloses a plurality of self-contained, disposable feline litter boxes housed in stacked relation within a container. Each litter box includes a removable top cover to expose the litter material contained within respective boxes. As each litter box is soiled, it may be removed from the container and disposed of, thereby exposing the next one for use.
U.S. Pat. No. 3,978,818 discloses a litter container containing a body of litter within a container of waterproof material and enclosed by an outer wrapper which may be opened to expose the open-top, substantially rectangular container for use.
U.S. Pat. No. 3,284,273 discloses an absorbent pad for use as a floor covering to absorb dripped or spilled liquids, and generally provides spaced-apart upper and lower layers within which is contained a liquid-retaining material which may be a sheet material or a granular material such as grains of absorbent clay. At least the upper layer is made of a liquid-permeable material, such as felt, so that liquids impinging thereon will pass therethrough and be absorbed by the intermediate liquid-retaining layer. The patent discloses that the lower layer may be lined with a liquid barrier material.
U.S. Pat. No. 4,173,046 discloses an absorptive and protective underpad for human patients utilizing a top cushioning layer which is perforated to admit liquids therethrough and a lower absorbent layer which will permit liquid flow into the absorbent layer and reduce to a minimum the generation and release of offensive odors from the absorbent layer.
One difficulty with many of the prior art animal litter devices, which utilize particulate litter material, is that the deposit of waste material tends to cause the litter to become foul-smelling and prompts the replacement of the entire box of litter after only limited use. Some of the prior art devices attempt to overcome this problem by providing, in lieu of particulate litter material, layers of absorbent fabric-like material which may be individually removed to expose fresh layers beneath, as may be seen in U.S. Pat. 4,250,834. However, these devices usually provide a hard, perforated platform on which the animal stands. Not only do such devices fail to adequately accomodate solid waste, but domestic animals such as cats are disinclined to use such litter boxes as they instinctively desire to cover up their waste and therefore favor litter boxes containing particulate material which they can paw to cover the deposited waste.